<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      console.log(!true);
      console.log(!false);
      console.log(!0); // !false==true

      console.log(Boolean(null)); //false
      console.log(!!null); //false

      /*  
        console.log(!!null); 
       1. console.log(!!fasle); 
       2. console.log(!true); 
       3. console.log(false); 
      */
    </script>
  </body>
</html>
